Metagenomic analysis of human-biting cat fleas in urban northeastern United States of America reveals an emerging zoonotic pathogen.

An infestation of cat fleas in a research center led to the detection of two genotypes of Ctenocephalides felis biting humans in New Jersey, USA. The rarer flea genotype had an 83% incidence of Rickettsia asembonensis, a recently described bacterium closely related to R. felis, a known human pathogen. A metagenomics analysis developed in under a week recovered the entire R. asembonensis genome at high coverage and matched it to identical or almost identical (> 99% similarity) strains reported worldwide. Our study exposes the potential of cat fleas as vectors of human pathogens in crowded northeastern U.S, cities and suburbs where free-ranging cats are abundant. Furthermore, it demonstrates the power of metagenomics to glean large amounts of comparative data regarding both emerging vectors and their pathogens.

Detection of Rickettsia monacensis and Rickettsia amblyommatis in ticks collected from dogs in Costa Rica and Nicaragua.

The neotropical climate of Central America provides ideal conditions for ticks, which may transmit several human pathogens, including spotted-fever group Rickettsia. Dogs may act as sentinels or reservoirs for human tick-borne diseases due to shared tick species. Here, ticks were collected from 680 client-owned dogs in Nicaragua and Costa Rica, and a total of 316 tick pools were investigated for Rickettsia infection by quantitative real-time PCR (qPCR) targeting the gltA gene. Subsequently, up to six further genomic targets (16S rDNA, gltA, sca4, ompA, ompB and the 23S-5S intergenic spacer) were investigated for Rickettsia species determination. The predominant tick species was Rhipicephalus sanguineus sensu lato (s.l.) (19.9% of dogs infested in Costa Rica, 48.0% in Nicaragua), followed by Ixodes boliviensis (3.1% in Costa Rica / none in Nicaragua) and Amblyomma ovale (4.8% in Costa Rica, 0.9% in Nicaragua). In total, 22 of 316 tick pools containing 60 of 1023 individual ticks were Rickettsia-positive as determined by qPCR, resulting in a minimum infection rate (MIR) of 2.2%. In detail, MIR in Rh. sanguineus s.l. was 0.7% (7/281 pools), in I. boliviensis 33.3% (12/13 pools) and in A. ovale 9.7% (3/22 pools). For 11 of 12 positive I. boliviensis pools and one of six positive Rh. sanguineus s.l. pools, the species could be determined as R. monacensis. R. amblyommatis was identified in one Rh. sanguineus s.l. pool from Costa Rica and one A. ovale pool from Nicaragua. Nine of 12 R. monacensis-positive tick pools were collected in San Rafael de Heredia, Costa Rica, indicating a high local occurrence in this area. This study supports recent evidence that R. monacensis is present on the American continent. Its high local occurrence among dog-associated I. boliviensis, which may also parasitize humans, in Costa Rica gives cause for concern, as R. monacensis is also pathogenic to humans.

Wild and domestic animals likely involved in rickettsial endemic zones of Northwestern Colombia.

Between 2006 and 2008, three outbreaks of human rickettsiosis occurred in Northwestern Colombia (municipalities of Necoclí, Los Córdobas and Turbo), with case fatality rates between 27% and 54%. The aim of this study was to determine previous exposure of wild and domestic animals to spotted fever group (SFG) rickettsiae through serological tests, to detect rickettsial evidence in their ectoparasites, and to analyze their possible role in the epidemiology of rickettsial diseases in this zone of the country. A cross-sectional association study was performed from 2010 to 2011. Blood and ectoparasite samples were collected from domestic animals and small mammals. A statistically significant association (p<0.05) between seropositive animals and the study zones was observed. A total of 2937 ticks, 672 fleas and 74 lice were collected and tested in pools by PCR. The minimum infection rate (MIR) of the positive pools was 5% in ticks, 4% in fleas, and 0% in lice. Phylogenetic analyses showed circulation of three 4.Rickettsia species: R. felis in fleas, and R. bellii and Rickettsia sp. strain Atlantic rainforest, both in Amblyomma ovale ticks. In conclusion, this study demonstrated the occurrence of SFG rickettsiae in domestic, synanthropic and wild animals, and suggests the use of equines and canines as good sentinels of infection, in the study zone. We speculate that a transmission cycle exist involving rodents in the areas where these outbreaks have occurred. Tomes' spiny rats (Proechimys semispinosus) and common opossums (Didelphis marsupialis) could be good candidates as amplifier hosts for SFG rickettsiae in enzootic/endemic zones.

Rickettsia amblyommatis infecting ticks and exposure of domestic dogs to Rickettsia spp. in an Amazon-Cerrado transition region of northeastern Brazil.

This study was performed in Maranhão state, a transition area two Brazilian biomes, Amazon and Cerrado. During 2011-2013, 1,560 domestic dogs were sampled for collection of serum blood samples and ticks in eight counties (3 within the Amazon and 5 within the Cerrado). A total of 959 ticks were collected on 150 dogs (9.6%). Rhipicephalus sanguineus sensu lato (s.l.) was the most abundant tick (68% of all collected specimens), followed by Amblyomma cajennense sensu lato (s.l.) (12.9%), Amblyomma parvum (9.2%), and Amblyomma ovale (5.2%). Other less abundant species (<1%) were Amblyomma oblongoguttatum, Rhipicephalus microplus, Haemaphysalis juxtakochi, and Amblyomma rotundatum. Females of A. cajennense s.l. ticks were morphologically identified as A. cajennense sensu stricto (s.s.) or A. sculptum. Molecular analyses of 779 canine ticks revealed three Rickettsia species: Rickettsia amblyommatis in 1% (1/100) A. cajennense s.l., 'Candidatus Rickettsia andeanae' in 20.7% (12/58) A. parvum, Rickettsia bellii in 6.8% (3/44) A. ovale and 100% (1/1) A. rotundatum ticks. An additional collection of A. sculptum from horses in a Cerrado area, and A. cajennense s.s. from pigs in an Amazon area revealed R. amblyommatis infecting only the A. cajennense s.s. ticks. Serological analysis of the 1,560 canine blood samples revealed 12.6% canine seroreactivity to Rickettsia spp., with the highest specific seroreactivity rate (10.2%) for R. amblyommatis. Endpoint titers to R. amblyommatis were significantly higher than those for the other Rickettsia antigens, suggesting that most of the seroreactive dogs were exposed to R. amblyommatis-infected ticks. Highest canine seroreactivity rates per locality (13.1-30.8%) were found in Amazon biome, where A. cajennense s.s. predominated. Lowest seroreactivity rates (1.9-6.5%) were found in Cerrado localities that were further from the Amazon, where A. sculptum predominated. Multivariate analyses revealed that canine seroreactivity to Rickettsia spp. or R. amblyommatis was statistically associated with rural dogs, exposed to Amblyomma ticks.

Limited Evidence for Rickettsia felis as a Cause of Zoonotic Flea-Borne Rickettsiosis in Southern California.

Over 90% of human flea-borne rickettsioses cases in California are reported from suburban communities of Los Angeles and Orange counties and are presumed to be associated with either Rickettsia typhi or Rickettsia felis infection. Ctenocephalides felis (Bouché) is considered the principal vector for both rickettsiae, and R. felis has largely replaced R. typhi as the presumptive etiologic agent based on the widespread incidence of R. felis in cat flea populations. However, with no evidence to confirm R. felis as the cause of human illness in southern California, coupled with recent findings that showed R. felis to be widespread in cat fleas statewide, we propose that this hypothesis should be reconsidered. Evidence of only limited numbers of R. typhi-infected cat fleas in the environment may indicate a very rare infection and explain why so few cases of flea-borne rickettsioses are reported each year in southern California relative to the population.

The ecological niche of Dermacentor marginatus in Germany.

The ixodid tick Dermacentor marginatus (Sulzer, 1776) is endemic throughout southern Europe in the range of 33-51 (°) N latitude. In Germany, however, D. marginatus was exclusively reported in the Rhine valley and adjacent areas. Its northern distribution limit near Giessen is located at the coordinates 8.32 (°) E/50.65 (°) N. Particularly with regard to the causative agents of rickettsioses, tularemia, and Q fever, the observed locations as well as the potential distribution of the vector D. marginatus in Germany are of special interest. Applying a dataset of 118 georeferenced tick locations, the ecological niche for D. marginatus was calculated. It is described by six climate parameters based on temperature and relative humidity and another six environmental parameters including land cover classes and altitude. The final ecological niche is determined by the frequency distributions of these 12 parameters at the tick locations. Main parameters are the mean annual temperature (frequency distribution characterized by the minimum, median, and maximum of 6.1, 9.9, and 12.2 (°)C), the mean annual relative humidity (73.7, 76.7, and 80.9 %), as well as the altitude (87, 240, 1108 m). The climate and environmental niche is used to estimate the habitat suitability of D. marginatus in Germany by applying the BIOCLIM model. Finally, the potential spatial distribution of D. marginatus was calculated and mapped by determining an optimal threshold value of the suitability index, i.e., the maximum of sensitivity and specificity (Youden index). The model performance is expressed by AUC = 0.91.

Diversity of Babesia and Rickettsia species in questing Ixodes ricinus: a longitudinal study in urban, pasture, and natural habitats.

In a previous study, our group investigated the Babesia spp. prevalence in questing Ixodes ricinus ticks from nine city parks in South Germany in the years 2009 and 2010. We showed predominant prevalence of B. venatorum (in previous literature also known as Babesia sp. EU1), especially in those parks in a more natural condition and with occurrence of large wild animals, such as roe deer. To obtain longitudinal data and to broaden the knowledge about this pathogen, further investigations were carried out in 2011 and 2012 in four of those city parks. Two additional habitat types were chosen for comparison of prevalence data and species analysis focusing on occurrence of potential reservoir hosts. A total of 10,303 questing I. ricinus were collected in four city parks, a pasture, and a natural area in Bavaria, and a representative number of samples were investigated for prevalence of DNA of Babesia spp. (n=4381) and Rickettsia spp. (n=2186) by PCR. In the natural and pasture area, a significantly higher Babesia spp. prevalence compared to the urban area was detected. The natural area revealed sequences of B. microti, B. venatorum, and B. capreoli. In the pasture and urban habitat, predominantly B. venatorum was found, whereas B. capreoli was less frequent and only one B. microti-infected tick was found. All B. microti sequences were 100% identical to the zoonotic Jena/Germany strain. For Rickettsia spp., the significantly highest prevalence was also detected in the natural and pasture areas, whereas lower prevalence was found in the urban area. Sequence analysis revealed R. helvetica (98%) and R. monacensis (2%). Prevalence rates and occurrence of Babesia spp. and Rickettsia spp. differed in urban, pasture and natural sites, most likely depending on the habitat structure (natural or cultivated) and therefore on the appearance and availability of reservoir hosts like roe deer or small mammals.

Spotted fever group Rickettsiae in ticks in Cyprus.

In two surveys conducted from March 1999 to March 2001 and from January 2004 to December 2006, a total of 3,950 ticks (belonging to ten different species) were collected from seven domestic and wild animals (goat, sheep, cattle, dog, fox, hare, and mouflon) from different localities throughout Cyprus. In order to establish their infection rate with Spotted Fever Rickettsiae (SFG), ticks were pooled and tested by polymerase chain reaction targeting gltA and ompA genes, followed by sequencing analysis. When tick pools tested positive, individual ticks were then tested one by one, and of the 3,950 ticks screened, rickettsial DNA was identified in 315 ticks (infection rate, 8%). Five SFG Rickettsiae were identified: Rickettsia aeschlimannii in Hyalomma marginatum marginatum, Rickettsia massiliae in Rhipicephalus turanicus and Rhipicephalus sanguineus, Rickettsia sibirica mongolotimonae in Hyalomma anatolicum excavatum, and a Rickettsia endosymbiont of Haemaphysalis sulcata (later described as Rickettsia hoogstraalii) in Haemaphysalis punctata. Two additional genes, 17 kDa and ompB, were targeted to characterize a new genotype of "Candidatus Rickettsia barbariae" genotype in R. turanicus, designated here as "Candidatus Rickettsia barbariae" Cretocypriensis. These results confirm the presence of a spectrum of SFG Rickettsiae on the island. Further studies are necessary to gain better knowledge on the epidemiology of SFG Rickettsiae in Cyprus.

Tick-borne lymphadenopathy (TIBOLA) acquired in Southwestern Germany.

BACKGROUND: Tick-borne lymphadenopathy (TIBOLA) was first described in 1997 in a patient in France. The causative agent, Rickettsia slovaca, is transmitted by Dermacentor ticks. CASE PRESENTATION: In southwestern Germany we encountered a patient with a tick bite at the dorsal scalp that resulted in an eschar and nuchal lymphadenopathy. Additionally, fever, malaise as well as elevated inflammatory markers and transaminases occurred. The characteristic clinical picture along with positive antibody testing for rickettsiae of the tick-borne spotted fever group strongly suggest the diagnosis TIBOLA. CONCLUSION: Human rickettsioses are emerging infections. Clinicians should be aware of TIBOLA as a newly described rickettsial disease. As in our case, TIBOLA may be encountered in regions/countries where R. slovaca and Dermacentor ticks are prevalent but autochthonous acquisition was not described before.

Rickettsial infection in domestic mammals and their ectoparasites in El Valle de Antón, Coclé, Panamá.

The present research evaluated the presence of Rickettsia spp. on ectoparasites of horses and dogs (using PCR techniques), and their sera (using immunofluorescence assay) in El Valle de Antón town in Panama. A total of 20 horses and 20 dogs were sampled, finding four species of ectoparasites on dogs (the ticks Rhipicephalus sanguineus, Amblyomma ovale, Amblyomma oblongoguttatum, and the flea Ctenocephalides felis), and two tick species on horses (Amblyomma cajennense and Dermacentor nitens). DNA of Rickettsia amblyommii was found in pools of A. cajennense, D. nitens, and R. sanguineus, while Rickettsia felis was detected in C. felis pools. Overall, 70% (14/20) and 65% (13/20) of the horses and dogs, respectively, were seroreactive (titer ≥ 64) to spotted fever group rickettsiae. Sera from six dogs and five horses reacted to R. amblyommii antigens with titers at least four-fold higher than those for the other antigens tested (Rickettsia bellii, Rickettsia parkeri, Rickettsia rhipicephali, R. felis, and R. rickettsii). These serological results, coupled with our molecular findings, suggest that these dogs and horses were infected by Rickettsia amblyommii. More studies need to be realized afford to identify the Rickettsia species responsible for other serological and molecular positive results, and their ecological importance.

Associations between coinfection prevalence of Borrelia lusitaniae, Anaplasma sp., and Rickettsia sp. in hard ticks feeding on reptile hosts.

An increasing number of studies reveal that ticks and their hosts are infected with multiple pathogens, suggesting that coinfection might be frequent for both vectors and wild reservoir hosts. Whereas the examination of associations between coinfecting pathogen agents in natural host-vector-pathogen systems is a prerequisite for a better understanding of disease maintenance and transmission, the associations between pathogens within vectors or hosts are seldom explicitly examined. We examined the prevalence of pathogen agents and the patterns of associations between them under natural conditions, using a previously unexamined host-vector-pathogen system--green lizards Lacerta viridis, hard ticks Ixodes ricinus, and Borrelia, Anaplasma, and Rickettsia pathogens. We found that immature ticks infesting a temperate lizard species in Central Europe were infected with multiple pathogens. Considering I. ricinus nymphs and larvae, the prevalence of Anaplasma, Borrelia, and Rickettsia was 13.1% and 8.7%, 12.8% and 1.3%, and 4.5% and 2.7%, respectively. The patterns of pathogen prevalence and observed coinfection rates suggest that the risk of tick infection with one pathogen is not independent of other pathogens. Our results indicate that Anaplasma can play a role in suppressing the transmission of Borrelia to tick vectors. Overall, however, positive effects of Borrelia on Anaplasma seem to prevail as judged by higher-than-expected Borrelia-Anaplasma coinfection rates.

[Ecology and epidemiology of tick-borne infections in the Primorsky Krai].

Interrelation of parasitological and epidemiological estimations of potential danger of different territories Primorsky Krai concerning presence of natural foci of tick-borne diseases is discussed. Comparative analysis of long-term dynamics of the tick-borne diseases' sickness rate in comparison with long-term dynamics of the vector ticks' abundance has been carried out.

[Ecology of Rickettsia and epidemiology of rickettsioses].

Questions of ecology of obligate-transmissible rickettsioses causative agents and their natural environment--organism of blood-sucking arthropoda (ixodes, gamasid ticks, harvest ticks, lices, fleas) are considered. In tick organism Rickettsia are propagated, and transphase and transovarial transmission of rickettsia maintains population in natural focuses. The relationship between Rickettsia ecology and rickettsioses epidemiology is evident. Data about new-revealed and recurrent rickettsioses and role of molecular-biological and genetical methods of Rickettsia detection are represented. Biological and social factors having influence on appearance of new and recurrent rickettsioses are determined with the aim of their prediction.

[Taxonometry, ecology and evolutional relation of rickettsia].

Ecology of Rickettsia is main direction of researches of RAMS academician I. V. Tarasevich and her team. Characteristics of alpha 1-Protobacteriae--parasites of eukaryotic cells--given in the work. The accent to Rickettsia characteristics in relation of their evolution relationship with eukaryote mitochondria is made. Main directions of researches in Q-fever, Tsutsugamushi fever, rickettsioses of tick-borne spotted fever (TSF) group, performed in our country under direction of RAMS academician I. V. Tarasevich, are represented. Results of study with the use of tick experimental model, monoclonal antibodies and genetical methods of TSF group Rickettsia, revealed in Siberia and Far East (focal territories of tick-born rickettsioses) and also in territories with the absence of this infection in Russia and Kazakhstan, are given.

[Medical geography in study of rickettsioses].

Shorts resume of medical-geographical studies of Q-fever, tsutsugamushi fever, rickettsioses of tick-borne spotted fever is represented. Influence of biotic and abiotic factors on spread and landscape tropism of infection agents is considered. Types of focuses on endemic territories are determined, regions with high risk of infection for humans are detected.

Amblyomma triste Koch, 1844 (Acari: Ixodidae): hosts and seasonality of the vector of Rickettsia parkeri in Uruguay.

Amblyomma triste Koch, 1844, the tick species most frequently involved in human bites in Uruguay, has been implicated as a vector of human rickettsiosis. Seasonal abundance of adult A. triste was examined by standard flagging at three sites where human tick bites and cases of the disease have been reported. Adult tick activity occurred from August to February (end of winter to mid summer in the southern hemisphere) with a peak in spring. Activity declined in step with decreasing temperatures and photoperiod during winter. This period of activity coincides with seasonal outbreaks of human rickettsiosis in the region. In a small mammal survey, the Sigmodontinae rodents Scapteromys tumidus (Waterhouse, 1837) and Oxymycterus nasutus (Waterhouse, 1837) and the small marsupial Monodelphis dimidiata (Wagner, 1847) were the main hosts for immature A. triste. Immature ticks were observed on hosts in November, well within the period of peak adult abundance. In stored collections, immature ticks were most often collected from January to March. These data suggest that one generation might be completed in 1 year. The main animal host for adult A. triste at our study sites was the domestic dog. Humans were afflicted by the tick in rural and suburban settlements where other host animals are scarce or extinct and where dogs are common.

Polygenic detection of Rickettsia felis in cat fleas (Ctenocephalides felis) from Israel.

The presence of Rickettsia felis, an emerging bacterial pathogen, was investigated in 79 cat flea (Cteno-cephalides felis) pools from Israel (5 to 20 fleas each) by polymerase chain reaction (PCR) and sequencing of 5 different genes. Amplified targets included both metabolic (gltA and fusA) and surface antigen (ompA, ompB, and the 17-kDa antigen) genes. R. felis DNA was detected in 7.6% of the flea pools. Two genotypes similar in their housekeeping gene sequences but markedly different in their surface antigenic genetic milieus were characterized. This is the first detection of this flea-transmitted rickettsia within its vector in Israel and the Middle East. Although no clinical case has been reported in human beings in Israel to date, these findings suggest that this infection is prevalent in Israel.

[The onset of chronic Lyme-borreliosis after the cure of tick-borne rickettsia infection in simultaneous infection]. / Razvitie khronichekogo Laim-borrelioza posle izlecheniia kleshchevogo rikketsioza pri odnovremennom infitsirovanii.

A case of a male patient with chronic Lyme borreliosis running with marked neurological symptoms (Garin-Bujardoux-Bannwarth syndrome) is reported. Two years before the disease manifestation the patient was infected by the tick with both borrelia and Rickettsia sibirica. The latter infection provoked an acute fever in tick-borne rickettsiosis immediately after the tick's bite. This masked development of Lyme borreliosis which manifested only 5 months later as a neurological disease. It is thought necessary to propose a rational scheme of antibiotic treatment of patients with tick-transmissible diseases.

Rickettsia africae, a tick-borne pathogen in travelers to sub-Saharan Africa.

BACKGROUND: African tick-bite fever occurs after contact with ticks that carry Rickettsia africae and that parasitize cattle and game. Sporadic reports suggest that this infection has specific clinical and epidemiologic features. METHODS: We studied patients who were tested for a rickettsial disease after returning from a visit to Africa or Guadeloupe. To assess the value of the microimmunofluorescence assay, Western blotting, and cross-adsorption assays, we compared the results of these tests in 39 patients in whom African tick-bite fever had been confirmed by the polymerase-chain reaction assay, cell culture, or both; 50 patients with documented R. conorii infection; and 50 blood donors. These diagnostic criteria were then applied to 376 additional patients who had returned from southern Africa and 2 who had returned from Guadeloupe and whose serum was being tested for rickettsial disease. RESULTS: In the 39 patients with direct evidence of R. africae infection, the combination of microimmunofluorescence assay, Western blotting, and cross-adsorption assays showing antibodies specific for R. africae had a sensitivity of 0.56; however, each test had a positive predictive value and a specificity of 1.0. An additional 80 patients were found to have an R. africae infection on the basis of these serologic criteria. Infections with R. africae were acquired by visitors to 11 African countries and Guadeloupe. The illness was generally mild and was characterized by a rash in 46 percent of the patients; the rash was usually maculopapular or vesicular and rarely purpuric. Ninety-five percent of patients had an inoculation eschar or eschars, and 54 percent of these patients had multiple eschars, a finding that is unusual in patients with rickettsial infection. CONCLUSIONS: In this series, R. africae was the cause of nearly all cases of tick-bite rickettsiosis in patients who became ill after a trip to sub-Saharan Africa.

The biology of rickettsiae.

Rickettsiae are bacterial obligate intracellular parasites ranging from harmless endosymbionts to the etiologic agents of some of the most devastating diseases known to mankind. Rickettsiae are primarily associated with arthropod vectors in which they may exist commensally and, in most cases, only accidentally infect humans. These fascinating microbes are the prototypical obligate intracellular parasites. Other than being extremely fastidious in their growth requirements, however, rickettsiae are typical gram-negative bacteria. Only a few intracellular parasites multiply within the cytoplasm of eukaryotic cells. In this environment, rickettsiae are provided with a rich source of biosynthetic precursors not normally encountered by free-living bacteria and have evolved a number of unique mechanisms to transport such metabolites as nucleotides and nucleotide sugars. The physiologic basis for their obligate parasitism, however, has remained elusive for > 90 years. Other than the obvious property of replicating inside eukaryotic cells, the molecular mechanisms of cellular damage are ill defined. The typhus-group rickettsiae multiply within host cells to great numbers without profound damage until lysis occurs. In contrast, the spotted fever-group rickettsiae spread rapidly from cell to cell by an actin-based motility. This property, in itself, is not sufficient to cause cell death, because avirulent spotted fever-group rickettsiae also spread by actin-based movement but do not cause lysis of the host cell. Despite the obvious limitations imposed by their obligate intracellular lifestyle and the current lack of methods for genetic manipulation, there are enough interesting biological properties of rickettsiae to offer an attractive area for research.